Gravimetric feeder



June 16, 1942. 5 NA 2,286,554

GRAVIMETRIC FEEDER Filed Aug. 18, 1939 3 Sheets-Sheet 1 1v VENTOR Edgar M babe/man,

A iromva June 16, 1942.

E. M.L|EBERMAN GRAVI'METRIC FEEDER Filed. Aug. 18, 1939 3 Sheets-Sheet 3 67 73 [NVENTOR Edyaiz L/kbrmarz ATTOIRNEY Patented June 16, 1942 STTES OFFICE GRAVHVIETRIC FEEDER Edgar M. Lieberman, Merriam, Kans, assignor to Eric W. Bacharach, Kansas City, Mo.

7 Claims.

This invention relates to dry material feeding apparatus, such, for example, as may be employed for supplying dry chemical in measured quantities in manufacture of treating solutions for water purification systems, for filling sacks with uniform volumes of material, or other uses for which it is desirable that dry material be fed in definite quantity by weight per unit of time.

In accomplishing such objects of my invention, I employ the principle of a beam balance for controlling and regulating the feed in response to variation in weight of the material in process of delivery through and from the apparatuses, together with details of structure and combination for rendering the principle effective for my purpose, preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig, 1 is a perspective View of apparatus embodying my invention, parts being broken away for better illustration.

Fig. 2 is a schematic view, in side elevation, of primary feed mechanism, and a balance beam forming part of the apparatus, illustrating conveyance of the material by a continuously movable conveyor element.

Fig. 3 is a longitudinal Vertical section generally on the line 3-3, Fig. 5.

Fig. 4 is an enlarged side elevation of the primary feed control switch mechanism.

Fig. 5 is a transverse vertical section on the line 5-5, Fig. 3.

, Fig. 6 is an enlarged perspective view of segregated part of a preferred form of bearing used in the apparatus.

Fig. '1 is a circuit diagram.

Fig. 8 is a side elevation of a modified form of primary feed control switch mechanism.

Fig. 9 is a circuit diagram for a modified form of control.

Referring more in detail to the drawings:

A designates the housing of the apparatus, including a frame, preferably of skeleton form, comprising top and bottom, side, end and intermediate horizontal rails [-2, 3-4, 5-6, 1 and. 8. 9-10 and H-l2 designate vertical end and intermediate rails, preferably of angle-iron and welded or otherwise connected to form a rigid carrying structure, the horizontal bottom rails 3-4 and intermediate vertical side rails ll-IZ being preferably connected by diagonal struts [3-14 to stiffen and brace the structure.

Rigidly secured to the vertical and intermediate rails 9-H], ll-l2 and to the horizontal end rail 8, preferably by welding, are trunnion bars l5-I6, which extend forwardly from the end of the frame to slightly beyond the vertical intermediate rails II and I2 and carry trunnion seats l1-l8 at their forward free ends.

Located between the end rail 8 and'trunnion bars l5-l6 is a U-shaped beam B comprising a base bar 19 and integral side legs 211-21, the latter extending forwardly a substantial distance beyond the ends of the trunnion bars and provided with trunnion seats 22-23 at their free ends.

The beam B is pivotally mounted on the bars I5-l6 by means of trunnions 24-25, preferably of the knife edge bearing type presently described, and the rear end of the beam is anchored by an adjustable counter-balance generally designated 0, but also presently described in detail, rocking movement of the beam being limited by a stop 8', preferably consisting of set screws carried by the end rail 8.

Pivotally mounted on the beam B is a platform D, comprising spaced end rolls 26-21 fixed to shafts 28-29, rotatably mounted in bearings 33-31 carried by spaced longitudinal bars 32-33, and rigid transverse spreaders 34 secured to the longitudinal bars and extending between the runs of a continuous conveyor belt 35 that is run over the rolls 26-21. V--belts 36 carried by the rolls 26-21 serve to support the conveyor belt between the rolls.

Fixed to the bars 32-33 are hanger rods 31-38 suspending a shelf 39 on which a motor 40 is sup.- ported. Run over a sprocket wheel 4| on the shaft 42 of a speed reducer 43 operatively connected with the motor 40, and over a larger sprocket wheel M fixed on the roll 21, is 'a chain belt 45 whereby the conveyor belt is carried to travel continuously over the platform inresponse to rotation of roll 21 when the motor is in operation.

Fixed to the roll spacing bar 33 is a' depending rod Mi which extends freely through an opening 41 in the shelf 39 and has a roller 48 projected into a U-shaped bracket 49 on a support 50 attached to the bottom side rail 4 of the housing frame for retaining the platform substantially horizontal throughout its length regardless of variation in angularity of the beam resulting from variation in load on the platform.

Fixed to the lcngitudinalbars 32-33 are risers 53 which extend vertically from the bars and inwardly over the rear end of the conveyor belt for support of a material guide E whereby dry material may be directed from the hopper mechanism to desired position on the conveyor belt. The guide E preferably comprises vertical side at the top, bottom and front end to receive a hopper nozzle for delivery of material onto the continuous belt between the sides of the guide,

so that material delivered to the belt may be carried thereby forwardly through the open end of the guide in elongated successive piles spaced sufliciently from the edges of the belt to avoid escape of the material therefrom.

As indicated by position of the trunnions 24 and 25, the forward end of the beam is weighted by the platform D and its suspended parts to permit lowering of the platform under its own weight unless restrained. Such restraint is, however, provided by the spring balance C, preferably consisting of a coil spring 57 hooked at its lower end to a pin 53 on a bar 59, non-rotatably but slidably mounted on a post 53 carried by the frame, and at its upper end to the base I9 of the beam by means of an overlying knife edge bearing member 6 I Rotatably keyed in a bracket 82 on the intermediate end frame bar 8 is a crank $3 having a screw shank 8d threaded into theupper end of the spring anchor bar 59 so that elevation of the platform may be adjusted by variation in angularity of the beam in response to regulation of tension of the counterbalancing spring by manipulation of the adjusting screw.

Referring now to that part of the mechanism for delivering material onto the platform, 65 designates a hopper F, including a body member 65 supported on the upper rear part of the housing A and having a throat 67 extending downwardly and forwardly into the rear end of the guide E a sufiicient distance to permit the outlet 68 thereof to remain housed within the guide for various positions of the platform. Extending downwardly and rearwardly into the body member 68 at the base of the hopper is a slide door 69 manually operable by a lever Hi pivotally mounted on the throat for regulating feed from the hopper into a measuring and agitating paddle wheel II mounted for rotation in an enlarged portion 'I'Z of the body member 66 for travel clockwise (Fig. 3) to permit the wheel to pick up measured quantities of material in the pockets between its plates, carry them over center and dump them into the spout portion of the throat for escape through the outlet 68 thereof onto the platform conveyor belt 35 under control of a gate I3 operable by a solenoid magnet 14. The solenoid core "55 (Fig. '7) is provided with a hook I (Fig. 1) adapted to selectively engage in spaced apertures Ti in an arm 18 on the gate I3 to determine extent of opening of the outlet 68 and, consequently volume of material discharged from the throat onto the conveyor according to position of the solenoid hook in the apertures of the gate arm.

The paddle wheel comprises spaced blades 19 on a hub 83 fixed on a shaft 8| journalled in bearings 82 in the sides of the body member and having one end extended to the exterior of the body member where it has a sprocket wheel 83 fixed thereto. Mounted on a shelf 8 within the upper rear portion of the frame is a motor 85 having a speed reduction transmission 86 including a shaft 8'! having fixed thereto a sprocket wheel 88 substantially smaller than the sprocket wheel on the shaft 8| of the feeding mechanism, and run over the sprocket wheels 83 and 88 is a chain belt 89 whereby the paddle wheel is rotated continuously when the motor is in operation.

The circuit for motor 85 includes a mercury switch 93 suspended from a clamp 8| having knife edge bearing on a bracket 92 carried on the frame, with the switch and clamp balanced as at 93 to permit operation of the switch with the least possible opposition to its functional movement in either direction, the switch proper being curved on a radius of its mounting to permit the mercury 94 in the switch to engage the circuit contacts 95 and 96 when the switch is in position for machine operation, but for opening the switch and interrupting operation of the machine when the switch has been swung out of circuit closing position in response to lowering of the platform under weight of material.

Operation of the switch is effected through a flexible connector 91 run over and attached to the rider 98 to which the switch clamp Si is secured by a fastening ea and-over a drum I00 rigidly secured to th beam arm 20 by welding or otherwise. The drum I69 has a bearing rider ISI extending axially from its outer side and overlying the knife edge member Hi2 on the bearing arm I5 coaxially with the corresponding bearing for the beam at the opposite side of the apparatus.

I prefer to form each of'the balance beams and the mercury switch clamp bearings heretofore mentioned of the knife edge type to permit their movement with the least possible resistance due to friction and, as to the beam and platform, prefer the universal type of mounting particularly illustrated in Fig. 6 of the drawings, wherein, for example, I82 designates a liner in one of the tubular beam or beam supporting arms, I03 a cylindrical stud fitting the liner for easy rotatable or longitudinal movement therein, but snug enough to avoid lost motion, H14 a shelf formed integrally with the stud, I95 a box having a boss I66 adapted to seat snugly but for free movement in a socket I07 in the shelf I04 and having a right-angular seat I68 in its interior, H59 a bearing block square in cross-section adapted to fit snugly in the seat I 88 with its corner edge He directed upwardly to form a knife edge bearing I I I for the rider I I2 on a beam arm or platform spacing rod mating with the beam arm or support as the case may be, with which the bearing just described is associated. With such bearing mechanism an misalignment of the balance beam or platform may be easily and automatically compensated for by corresponding moyement of the bearing parts in their support.

In the circuit diagram (Fig. 7) H3 designates a source .of current connected with the motor 49 that operates the conveyor belt on the platform through line wires |MIi5, so that the conveyor belt is operated continuously when the current is on. Connected in parallel with the circuit through the conveyor motor 59 by wires H6 and I I? is the solenoid l5 controlling the material feed door, and in parallel with the conveyor feed motor and the solenoid is the motor 85 to which current is supplied through the branch lines H8 and H9 from the lines H6 and l I? leading from the solenoid, the main feed motor circuit including a rhecstat 425 through which speed of the main feed motor may be regulated.

The mercury switch 99 is adapted for opening the circuit to the solenoid through the lines lit-H1, so that when the switch is opened in response to overload on the conveyor the main feed motor and solenoid will be cut out, thereby discontinuing the feed .and closing the delivery outlet from the hopper throat but continuing operation of the conveyor belt motor to permit accumulation of material on the belt to be discharged therefrom, lightening of the platform permitting the latter to resume its functional position and restoration of the feeding operation by reclosing .of the switch in response to reelevation of the platform. 7

In Fig. 8 I have illustrated mounting of the mercury switch directly on the control drum I00, the operation of the switch being as disclosed in description of its preferred mounting.

In Fig. 9 I have illustrated a circuit diagram in which the mercury switch is replaced by a variable condenser for varying the speed of the main feed motor 85, and in combination with which:

I2I designates an alternating current generator connected with the motor 50 by the lines H4 and H so the conveyor belt is operated continuously when the switch I22 is closed. Connected in parallel with the circuit through the conveyor motor is the feed motor 85 to which current is supplied through Wires I23 and I24, the feed motor circuit including a rheostat I25 for adjusting the speed of the feed motor to the required speed for feeding the material onto the belt. Also in the feed motor circuit is a variable plate type condenser I28 which replaces the mercury switch and which is mounted for rotation when the load on the belt varies so the variation of the load effects a corresponding variation in capacitive reactance of the condenser which adjusts the speed of the feed motor to compensate for the variation of material on the belt.

Assuming the apparatus to be assembled as described, when it is first started in operation the platform, being unloaded, is held yieldingly at the upper limit of its movement by the counterbalance spring, the mercury switch is closed and the solenoid inactive, thus holding the hopper outlet gate in closed position. When the current is turned on the conveyor belt motor starts the conveyor belt in operation, the solenoid is energized to open the outlet from the hopper and the main feed motor effects rotation of the paddle wheel to feed material through the hopper outlet onto the conveyor belt. As the apparatus continues in operation the material collects on the conveyor belt, as illustrated in Fig. 2, until a sufficient quantity has accumulated thereon to overload the platform and rock the beam. When the beam rocks, the drum I00, being fixed thereto, rotates slightly with the beam, thus rotating the mercury switch mounting and breaking contact between the mercury and the terminals 95 and 95 and opening the solenoid circuit. When this circuit is opened the solenoid immediately becomes deenergized and its spring thrusts the gate controlling material outlet from the hopper to closed position, shutting off flow of material to the conveyor belt and stops operation of the feeding wheel. The conveyor belt, however, continues in operation to discharge material from the belt to its receiving station, which may be a solution mixing tank, or other receptacle.

As soon as discharge of material from the conveyor belt lightens the platform sufiiciently to permit its restoration to normal elevation, the drum I!!!) will have reversed rotation of the mercury switch to restore contact between the terminals 95 and 96 and the circuit through the solenoid is restored, thereby effecting reopening of the material outlet. intermittent opening and closing of the material outlet is thereafter continued in like manner, with resultant uniformity of feed of the material by the conveyor belt.

, It is apparent that specific reference to details of structure of the apparatus has, in many instances, been' for clarity in descriptionwithout intent to limit the invention set out in the following claims thereto, as equivalent mechanisms may in most instances be employed without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. Apparatus of the character described, including a support, a beam fulcrumed on the support, a platform fulcrumed on the beam and provided with a traveling belt conveyor, said platform fulcrum point being substantially midway between the ends of the conveyor, a counterbalance for the beam, means for feeding material to the conveyor, and means for retaining the platform and conveyor substantially horizontal and in substantially fixed relation with said feeding means relatively to the longitudinal direction of the belt conveyor regardless of variation in angularity of the beam resulting from variation in load on the platform.

2. Apparatus of the character described, including a support, a beam fulcrumed on the support, a platform fulcrumed on the beam, a conveyor carried by the platform in a horizontal plane extending substantially through the fulcrum point of the beam, a stationary guide member, and a member fixed to the platform cooperative with the stationary guide member for retaining the platform substantially horizontal regardless of variation in angularity of the beam resulting from variation in load on the platform.

3. Apparatus of the character described, including a frame, a U-shaped beam including leg members fulcrumed on the frame, a platform between said beam legs fulcrumed on the beam legs in a horizontal plane extending substantially through the fulcrum points of the leg members, a conveyor movable on the platform, means connected with the beam for counterbalancing weight of the platform and conveyor, means for retaining said platform in horizontal position, and means for actuating the conveyor.

4. Apparatus of the character described including, a support, a beam fulcrumed on the support, a conveyor carrier, pulleys journalled on oppostie ends of the conveyor carrier, a conveyor running over said pulleys, means fulcruming the carrier on said beam, said fulcrum point being substantially between the runs of said belt and midway between the axes of said pulleys, and means retaining said conveyor carrier from tipping when the beam fulcrum responsive to load on the conveyor belt.

5. Apparatus of the character described including, a support, a beam fulcrumed on the support, a conveyor carrier, pulleys journalled in opposite ends of the conveyor carrier, a conveyor running over said pulleys, means fulcruming the carrier on said beam, said fulcrum point being substantially between the runs of said belt and midway between the axes of said pulleys, means retaining said conveyor carrier from tipping when the beam fulcrums responsive to load on the conveyor belt, a motor for operating the belt, means suspending the motor directly below the fulcrum point of said conveyor carrier, and a driving connection between the motor and one of said pulleys, said motor and its suspending means acting as a pendulum to cooperate-with said retaining means to prevent tipping of the conveyor carrier.

6. Apparatus of the character described including, a fulcrumed beam, a platform fulcrumed on the beam substantially in horizontal register with the beam and including a conveyor, a yieldable counterbalance for the beam responsive to variation in weight on the platform, and means limiting tilting movement of the platform on said beam throughout its vertical movement in response to weight on the conveyor.

'7. Apparatus of the character described ineluding, a support, a beam fulcrumed on the support, a platform fulcrumed on the beam substantially in horizontal register with the beam and provided with a travelling belt conveyor, a counterbalance for the beam, means for feeding material to the conveyor, means for retaining the platform and conveyor substantially horizontal regardless of variation in angularity of the beam resulting from variation of load on the platform, and means operable in response to variation in angularity of the beam controlling said feeding means.

EDGAR M. LIEBERMAN. 

